1. Field of the Invention
This invention relates to a line pipe provided with a lining laminate containing a pressure sensitive adhesive. Particularly, it relates to a line pipe usable for rehabilitation of various existing pipelines, transportation of an abrasive fluid such as slurry, particles, dredged sand and stone or the like, transportation of a corrosive fluid such as sea water, CO.sub.2 gas, sour gas or the like, transportation of stored water in water-power generation, transportation of service water and sewage, transportation of hot water in geothermal power generation, hot spring and the like.
2. Related Art Statement
At the present, a method wherein water reserved in a dam is led up to a position having a large water falling difference through a water passage tunnel and passed therefrom through a water pressure iron pipe to a power plant is adopted as a technique for the transportation of reserved water in water-power generation.
In such a known method, it is common to arrange a sand settling equipment on an inlet of the water passage tunnel for removing sand. Still, sand-containing water passes through the water pressure iron pipe at a high speed of 2.about.10 m/sec, so that there is a drawback that the wearing of the iron pipe becomes conspicuous. For example, in a connecting portion between the pipes through an expansion joint, an annular space for expansion is arranged for overcoming the temperature difference (about 80.degree. C.) accompanied with the difference between day and night, season change and the like. In this case, however, sand contained in the flowing water is entrapped into the annular space to cause a so-called strong erosion, and also this erosion is promoted due to cavitation produced by whirl flow, whereby the service life of the pipe is considerably shortened. Particularly, the settlement of earth and sand is apt to be caused in the annular space arranged in the connecting portion through the expansion joint. Considering, for example, a case that earthquake occurs at such a sedimentated state, the iron pipe slides in the axial direction of the pipe at such a state that sand is entrapped in the annular space. As a result, a rubber ring for sealing housed in the space is injured to cause water leakage.
In this connection, the inventor has previously proposed a method of rehabilitating the existing overage pipe as a technique for solving problems kept in the water pressure pipe in Japanese Patent laid open No. 61-282687. Even in this prior technique, however, it is an actual circumstance that the damage of the expansion joint due to the sliding of such a joint during the occurrence of earthquake can not sufficiently be prevented.
Namely, according to this prior technique, the portion corresponding to the above annular space forms a connecting portion in the lining, so that when rapid force such as earthquake or the like is applied to the connecting portion, the peeling and breakage of the connecting portion are apt to be caused, while the annular space is enlarged even under the action of moderate force such as temperature change or the like to cause the flowing of pressure sensitive adhesion layer disposed in the connecting portion and thinly stretch the lining tube. As a result, the lining tube becomes brittle and the service life of the pipe undesirably becomes shorter.
On the other hand, when aiming at the connecting portion between the above known line pipes, the lining structure, particularly the lining structure at the expansion joint portion has the following drawbacks:
At first, when the lining layer is not existent in the line pipe using the bellows or sleeve type expansion joint, the end portion of the pipe is apt to be broken by galling under an influence of sand and the like contained in the flowing water as previously mentioned, and also the sliding face of the sealing or the like is corroded to shorten the service life of the sealing.
In case of the line pipe provided with the lining layer, the influence of sand in the flowing water is less. However, since the lining tube is frequently bonded to the inner surface of the pipe through an adhesive, the lining tube and the adhesive layer can not cope with moderate stretching of the pipe accompanied with the temperature change, or the rapid sliding of the pipe due to earthquake or the like. In other words, the lining can not follow to the stretching of the expansion joint. For example, when the pipe is contracted due to the temperature drop (winter season, night) to enlarge the annular space, or when the pressure inside the pipe largely changes, a portion of the lining tube corresponding to the annular space portion in the joint is elongated to thin the thickness of the tube or form recess or protrusion. Further, a loading accompanied with the ordinary stretching is always added to the lining tube in addition to the above stretching, whereby the lining tube is ununiformized, and finally the degradation of the lining tube is promoted to shorten the service life of the pipe.
Even in case of the line pipe provided with the lining using the pressure sensitive adhesive sheet, it is impossible to supplement the pressure sensitive adhesive sheet by an amount in accordance with the increase of volume in the annular space portion produced in the contracting of the pipe, so that the lining layer is ununiformized or the peeling or breakage of the lining tube in the connecting portion between the pipes is caused to injury the sealing.
In general, defects such as rust, scale, scab and the like are existent in the inner surface of the line pipe and are usually made by voids. If the pipeline is formed by performing the lining at a void remaining state, high pressure gas, corrosion product and the like store in the void portions during the use of long period to cause blister in the lining layer, whereby the durability of the lining tube is lowered. Furthermore, the unadhesion portion of the lining is generated on a weld bead portion in the inner surface of the welded joint between the line pipes. Moreover, when the lining tube is drawn into the inside of the line pipe, there is caused a problem of peeling off the pressure sensitive adhesion layer from the lower portion of the lining tube.